The present invention relates to determining properties such as relative permeability to steam or combinations of steam, water or oil phases within cores of reservoir formations containing oil and water, and is also useful for measuring permeabilities to steam, water, and oil in well defined laboratory-derived porous media such as glass bead or sand packs. In this latter application the greater stability of laboratory-derived as contrasted with some natural systems permits measurements to be made of more subtle changes in three-phase relative permeabilities.
The relative permeability to the steam phase in the presence of water and residual oil plays a significant role in simulating reservoir production performance during a steam drive. It is important to determine this parameter as accurately as possible. Previously obtained values for steam permeability have been based on gas permeabilities in gas/liquid systems and to some extent on adjusted values obtained from history matching based on oil production data. Prior measurements of such permeability have been based on geothermal systems where there is no oil phase present or in conjunction with surfactant systems. Published work relating to external gas drive with vaporization present at various temperatures suggests that the gas phase permeability is only mildly sensitive to temperature. Quantitative differences between the various published results leave some doubt as to the appropriate value to use. There is a need for measurements of the permeability to steam and simultaneously to water for cores of reservoir formations in which the residual oil is present, as well as for systems in which oil is flowing.